A provider of e-mail services may process e-mail messages on behalf of many customers, or “senders,” and forward the messages to specified recipients over the Internet. These e-mail messages may be sent across the Internet through a number of mail servers operating in the provider's e-mail delivery system, depending on the volume of e-mail messages being processed and the capacity of the mail servers. The mail server may utilize the domain name system (“DNS”) to determine the remote mail system designated for the recipient's e-mail address and then utilize an e-mail protocol, such as the simple mail transport protocol (“SMTP”), to forward the e-mail message to the remote mail system.
In order to protect recipients from unsolicited junk or bulk e-mail, referred to herein as spam e-mail, the remote mail system may incorporate a variety of known anti-“spam” techniques to identify and mark such e-mails. Each e-mail message received by the remote mail system may be identified by both the sender's e-mail address as well as a source address, such as the Internet protocol (“IP”) address of the mail server from which is was sent. As part of the implemented anti-spam techniques, upon detecting a threshold number of e-mail messages identified as spam e-mail, the remote mail system may begin to mark all e-mail from the mail server as spam e-mail based on the IP address from which the e-mail message was received.
Ultimately, the remote mail system may begin to block all e-mail messages received from the mail server at that IP address. In addition, the remote mail system may share the IP address of the offending mail server with other remote mail systems through the use of a “blacklist.” Once blacklisted, a large number of remote mail systems may begin to mark all message from the IP address as spam e-mail or block all connections from the identified mail server. The actions of remote mail systems in regards to e-mail messages identified by an IP address may determine the “reputation” of the IP address. An IP address appearing on one or more blacklists or identifying a mail server used to send a large number of spam e-mails may be said to have a bad reputation. Conversely, an IP address not on a blacklist and/or considered benign by remote mail systems may have a good reputation.
A particular e-mail delivery system may have a limited number of IP addresses available for sending e-mail messages. In an e-mail delivery system supporting a large number of customers, many customers may share the same mail server(s) for outbound e-mails. If one customer sends a large number of spam e-mail messages, the IP address of the shared mail server may develop a bad reputation. This may affect how e-mail messages from other customers of the e-mail delivery system are regarded by remote mail systems, regardless of the content of their messages. A non-spamming customer may still find that their e-mail messages are blocked or marked as spam e-mail, even when the content of the messages is benign.
It is with respect to these and other considerations that the disclosure made herein is presented.